Combine harvesters have been used to efficiently harvest biomass for many years. Originally developed to eliminate the need for manual cutting and threshing, harvesters have evolved into large self-powered machines, able to simultaneously perform many steps at once. A modern combine harvester can now cut, thresh, and clean crop in one continuous operation.
Combine harvesters today provide the operator with a means to vary machine settings so that different crop conditions may be accommodated. In order to achieve the highest capacity and efficiency of the harvesting machine, the harvester ground speed must be controlled according to the varying conditions of crop height, density and entanglement. This control is normally achieved by an operator, who depending on his or her experience, visually judges the crop condition and adjusts the ground speed accordingly. However, crop conditions can vary widely in the same field, requiring the operator to make constant adjustments to ground speed in order to attempt to maintain the optimum machine capacity and efficiency. This constant adjustment by the operator is not only a burden on the operator, but makes it very difficult to maintain an optimal speed for a given crop condition. Furthermore, constant adjustments may pose a safety risk by drawing the operators attention away from the safe operation of the combine harvester.
One method of measuring the efficiency of a combine harvester harvesting grain is to measure the amount of grain lost over the back of the sieve component and over the straw walker assembly such as described in U.S. Pat. No. 4,036,065 herein fully incorporated by reference. U.S. Pat. No. 4,036,065 describes the use of sensors at locations across the rear of the sieve of a combine and the sound of grain kernels striking the sensor being picked up by a microphone, amplified, filtered and fed to a ratio computing device which calculates the total grain loss from the sampling. The calculated grain loss is then displayed to the operator who can then make the necessary adjustments. Similarly, U.S. Pat. No. 5,015,997, herein fully incorporated by reference, describes a method of measuring grain loss over the back of the sieve using a pulse pick-up or vibration pick-up type sensor. Other systems utilize piezoelectric transducers to detect grain loss over the back of the sieve component.
These prior art systems can account in some degree for the various factors of affecting the harvesting of the crop. Such devices, however, insufficient for determining the optimum ground speed for two reasons. First, while grain loss is to some degree a function of ground speed, it is more closely related to other machine settings such concave setting, rotor/cylinder speed, fan speed and sieves opening. Only after changes to these setting fail to reduce grain loss should the ground speed be adjusted in response to grain loss. Second, response to grain loss is reactive, with a 10-15 second delay between the time the crop is cut to the time the loss of that crop is detected. Other prior art system, besides grain loss, exist but they too are reactive. The present invention is positioned in front of the harvester and the crop conditions are detected 1-2 seconds prior to being cut, and therefore the control is proactive rather than reactive.
Single pendulum systems have been used at the front of the combine harvester or forage harvester to measure biomass height. The system usually consists of a simple frame having a hinge, a potentiometer, a hanging rod, and a deflector. The hinge securely holds the hanging rod to the frame, while allowing the rod to rotate. The potentiometer is connected to detect the angle of rotation between the frame and the rod. Finally the deflector is attached to the end of the rod, and deflects off biomass, allowing the height of the biomass to be determined given the angle of deflection read by the potentiometer. Although a single pendulum system can be applied to biomass other than grain, it can only determine biomass height and not other factors such biomass density and entanglement.
There are many factors affecting the harvesting of the biomass such as moisture content, varying density of biomass, the height of the biomass, the general quality of the biomass, and biomass entanglement. None of the prior art systems are able to detect and properly account for all of these factors while being applicable to a broad range of biomass such as grain, corn, or switchgrass. A method for the real time determination of biomass height, density, and entanglement is needed to determine the most efficient harvester speed.